The anticonvulsant activity of D-cycloserine is specific for tonic convulsions.

D-Cycloserine has been shown to exert anticonvulsant activity in maximal electroshock seizures. The purpose of the present study was to evaluate the spectrum of D-cycloserine anticonvulsant activity using other experimental models of epilepsy. D-Cycloserine induced a dose-related decrease in the incidence of tonic convulsions induced by 120 mg/kg of pentylenetetrazol. The ED50 of D-cycloserine for the inhibition of the tonic convulsions was 109 mg/kg. The anticonvulsant activity was specific for the D-isomer at L-cycloserine (400 mg/kg) had no effect on the tonic convulsions. D-Cycloserine had no effect on the pentylenetetrazol-induced clonic convulsions induced by either 70 or 120 mg/kg pentylenetetrazol, electrically induced nonkindled hippocampal seizures or kindled amygdala seizures. D-Cycloserine had no effect on strychnine-induced tonic convulsions. These results indicate that D-cycloserine is inactive against clonic convulsions and may be active only against tonic convulsions mediated by brainstem sites.